Fig 4.

UL36USP deubiquitinates TRAF3. (A) HEK293T cells were transfected with HA-Ub, TRAF3-Flag along with empty vector, UL36USP-Myc, or C40A-Myc. Twenty-four hours posttransfection, cells were infected with SeV or mock infected. Flag-tagged TRAF3 was immunoprecipitated using an anti-FLAG antibody and subjected to immunoblot (IB) analysis using an anti-HA antibody to detect ubiquitination of TRAF3. (B) UL36 deubiquitinates both K48- and K63-linked polyubiquitin chains of TRAF3. TRAF3-Flag, UL36USP-Myc, and HA-Ub or the linkage-specific ubiquitin HA-K63-Ub or HA-K48-Ub expression plasmid was transfected as indicated. After SeV infection, co-IP assays were performed to detect the ubiquitination of TRAF3. (C) Co-IP experiments indicated that UL36USP inhibited the SeV-mediated recruitment of TBK1 by TRAF3.